title: Preserved oscillatory response but lack of mismatch negativity in patients with disorders of consciousness.
abstract: OBJECTIVE
  The diagnostic validity of non-phase-locked oscillations (NPLOs) and mismatch negativity (MMN) in an oddball task for assessing attentional reactivity in patients with disordered consciousness was examined.
  
  
  METHODS
  Patients in a minimally conscious (MCS, n = 6) or vegetative (VS, n = 16) state and healthy controls (n = 15) were assessed. MMN and NPLOs were analyzed with single-subject, non-parametric statistics.
  
  
  RESULTS
  In 11 healthy controls and 2 VS patients, MMN was detected. More subjects showed NPLO differences in the alpha than in the theta or beta frequency ranges. In 14 healthy controls, 4 MCS patients, and 5 VS patients, lower amplitudes after deviants were found in the alpha frequency range. One healthy subject and one VS patient showed higher amplitudes after deviants.
  
  
  CONCLUSIONS
  Neither ERPs nor NPLOs could reliably distinguish MCS from VS patients. However, NPLOs were more sensitive than ERPs for detecting significantly different activity, and they possibly identified preserved processing better than ERPs.
  
  
  CONCLUSIONS
  Intact neurophysiological attentional responses observed in the NPLOs of VS patients may indicate a need for other diagnostic techniques. Inter-individual differences in the direction of the effect should be considered as normal variance.
authors.affiliation: Department of Psychology and Center for Neurocognitive Research, University of Salzburg, Salzburg, Austria. yvonne.hoeller@sbg.ac.at
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Höller
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bergmann
authors.forename: Martin
authors.initials: M
authors.lastname: Kronbichler
authors.forename: Julia Sophia
authors.initials: JS
authors.lastname: Crone
authors.forename: Elisabeth Verena
authors.initials: EV
authors.lastname: Schmid
authors.forename: Stefan
authors.initials: S
authors.lastname: Golaszewski
authors.forename: Gunther
authors.initials: G
authors.lastname: Ladurner
mesh_terms: D000328:Adult; D000368:Aged; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000175:diagnosis* / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric